plastic wear strip
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Posted by: AdrianT ® 04/04/2007, 02:26:48 Author Profile eMail author Edit

One of the machines we manufacture is used usually in the copper winning process. They are called cathode stripping machines. Simple machines with 2 sets of chain conveyors. The chain has rollers that run on a 50 x 10 carbon steel flat bar on top of a channel. The flat bar is bolted onto the flange of the channel with counter sunk cap screws. At the bottom is another kind of rail but is not a concern. Our requirement: We need a sort of a plastic (urethane?/polyethelene?) to replace the 50 x 10 flat bar. This would be to reduce the coefficient of friction. The width must remain 50mm but the thickness can be a fair amount thicker, perhaps to 20/30mm or more. The wear strip would probably have to be bolted down. The chain itself is not incredibly heavy but the cathodes themselves would exert a force of about 95 kg (per side, on the chain - 190kg total mass) spaced at anything from 90mm to 285mm depending on the machine. Speed of the chain is very slow. The sprockets rotate at only 2.5 rpm. The process is stop/start depending on the pitch - every 90 to 285mm. I have zero experience in any type of plastics but I would imagine there would be a solution that would be able handle the wear and tear of this type of operation. The machines operate usually about 16 hours/day, 7 days/week, 365 days/year. I have been recommended PA6SA as a grade of plastic that would take the abuse. I also have a sample of PE300 but I believe that this would probably not be up to the job. Any help from someone with plastic experience would be much appreciated. There seems to be a huge amount of people dealing with plastics but most of the people I've dealt with don't actually have a clue about the different grades themselves. I know almost nothing about plastic.

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Re: plastic wear strip
Re: plastic wear strip -- AdrianT	Post Reply	Top of thread	Forum

Posted by: jboggs ® 04/05/2007, 18:49:35 Author Profile eMail author Edit

There are many companies in the business of making plastic guide tracks for roller chain. Try: https://www.valu-guide.com/ or https://www.murtfeldt.com/en/ or https://www.fennerdrives.com/guides/trackstar_uhmw_guides.asp Also check ThomasRegister.com for roller chain guides. You'll get a list a mile long. Look in Mcmaster-Carr (mcmaster.com). If they don't have it you don't need it. Also contact some local power transmission distributors such as Motion Industries or others in your yellow pages. One design question though - it sounds like the chain you describe is "sliding" along the track, rather than "rolling" along the track. Is that correct? If so, you should consider a design change to use a chain with oversize rollers so it will roll rather than slide. One other hint - a company called Phymet, Inc. makes a plastic roller chain idler sprocket that also dispenses lubricant on the chain as it touches it. A truly neat way of lubricating the chain, decreasing power requirements, and increasing its life. Hope that helps.

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Re: Re: plastic wear strip
Re: Re: plastic wear strip -- jboggs	Post Reply	Top of thread	Forum

Posted by: AdrianT ® 04/06/2007, 02:29:38 Author Profile eMail author Edit

The chain has oversize rollers. Diameter 47.5 mm with 40mm side plates. The chain is very big with a pitch of about 95mm so it's a big boy. It doesn't need a guide as such, just a wear strip. The chain moves very slowly and because of it's size, doesn't wonder off the wear strip. Thanks for the advice guys.

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Re: plastic wear strip
Re: plastic wear strip -- AdrianT	Post Reply	Top of thread	Forum

Posted by: Marky ® 04/04/2007, 07:42:47 Author Profile eMail author Edit

I think that you are on the right track....get samples and test them. There are all sorts of loaded plastics out there. By "loaded" I mean with a graphite or Teflon etc.. impregnated in them. Call a plastics manufacturer and talk to their apps people or have one of them visit and see your application...learn something from them. It sounds like a fix that you want to do only once and right Good luck Modified by Marky at Wed, Apr 04, 2007, 07:43:56

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Re: Re: plastic wear strip
Re: Re: plastic wear strip -- Marky	Post Reply	Top of thread	Forum

Posted by: AdrianT ® 04/04/2007, 08:00:48 Author Profile eMail author Edit

Ok, thanks. It's a mission to actually find people that know what they're talking about. I have spoken to a few suppliers but their only advice is from experience gained in other applications (which are not related - like linings on a coal chute) and they cannot even tell me any form of hardness values (Brinell/shore?) or abrasion resistance. This seems to be a problem throughout South Africa. I guess that's why we're still 3rd world... Yes, a strip that lasts a week would be bad news. The machines are going to be used in the DRC.

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Re: Re: Re: plastic wear strip
Re: Re: Re: plastic wear strip -- AdrianT	Post Reply	Top of thread	Forum

Posted by: Marky ® 04/04/2007, 08:43:10 Author Profile eMail author Edit

Oh I see...tough to get a hold of some good resources. Give this stuff a try....I've used both of these. UHMW (Ultra-High Molecular Weight) Polyethylene or MDS-Filled Nylon 6. Both of these can be found in a replaceable snap-on strip form.

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Re: Re: Re: Re: plastic wear strip -- Marky	Post Reply	Top of thread	Forum

Posted by: AdrianT ® 04/04/2007, 09:06:48 Author Profile eMail author Edit

Ok, thanks again. I'll see what I can get hold of. Sure it won't be a problem. Have a good day further. Cheers :-)

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